We also found that the subdwarf distance moduli
of [1]} were systematically smaller than the other literature values for low-metallicity clusters with \([Fe/H]<-1.2\) . The average difference increased with decreasing metallicity and reached about 0.30 mag
for the lowest-metallicity clusters. In order to correct this bias, we fitted a linear relation between the difference in distance modulus and metallicity to the data and shifted the [1]} distance moduli
upwards to bring them into agreement with the other literature data.
We finally shifted the distances that [3]} derived from CMD fitting down by 0.10 mag since we found a systematic bias of this size when comparing their distances with other literature distances.
